High load average with kswapd and I/O wait

📖 ~1 min read

Table of contents

1. Symptom & Impact
2. Environment & Reproduction
3. Root Cause Analysis
4. Quick Triage
5. Step-by-Step Diagnosis
6. Solution – Primary Fix
7. Solution – Alternative Approaches
8. Verification & Acceptance Criteria
9. Rollback Plan
10. Prevention & Hardening
11. Related Errors & Cross-Refs
12. References & Further Reading

Symptom & Impact

Load average remains elevated and user transactions degrade during peak periods.

Environment & Reproduction

RHEL 7 app server where batch jobs and online traffic contend for memory and disk.

Root Cause Analysis

Combined memory pressure and slow storage produce high iowait and scheduler queue buildup.

Quick Triage

Check top, iostat -x, vmstat, and sar to identify dominant bottleneck dimension.

Step-by-Step Diagnosis

Trace top processes, inspect journalctl for kernel reclaim events, and confirm storage latency trend.

Solution – Primary Fix

Throttle batch concurrency, optimize memory usage, and relocate heavy I/O paths to faster storage.

Solution – Alternative Approaches

Apply cgroups/resource controls and tune I/O scheduler parameters per device profile.

Verification & Acceptance Criteria

Load average aligns with CPU core count and p95 response time returns within SLO.

Rollback Plan

Undo recent tuning settings and restore previous scheduler/cgroup config if regressions appear.

Prevention & Hardening

Separate batch and latency-sensitive workloads and maintain capacity guardrails.

Related Errors & Cross-Refs

High iowait, blocked process alerts, periodic application timeouts during batch windows.

Related tutorial: View the step-by-step tutorial for rhel-7.

View all rhel-7 tutorials on the Tutorials Hub →

Browse all common problems & solutions on the Tutorials Hub.

References & Further Reading

RHEL tuning profiles, sar/iostat analysis guides, workload isolation best practices.